The invention relates to a novel apparatus including a new article of manufacture embodying a glass surface having a raised optical pattern, especially an array of spherical microlenses, integral therewith. By properly proportioning the optics of the array, a 1:1 erect conjugate image may be produced, thereby making the device particularly applicable to compact photocopiers.
Lenticular elements have been molded on both glass and plastic surfaces for various purposes. Thus, such elements perform a light focusing or controlling function in the panels or faces of light integrators and light refractors. They may also function primarily to scatter ambient light, as in projection screens and in cathode ray tubes.
Optic devices, such as just described, tend to exert a single optic effect, e.g., refracting or bending light rays which strike the element. The devices embody no imaging capability or concept. In general, the molded elements are rather large. Further, they do not normally require critical attention to precise accuracy such as required for image transmission in a photocopier for example.
Recently, it has been proposed to produce a strip lens array by molding a plurality of tiny microlenses on a plastic surface. The microlenses would be molded in rows and columns on two parallel plastic lens plates. With proper attention to spacing, lens size and other factors, a very compact and efficient imaging device could be produced.
As used herein, the term "array" refers to arrangements of lenses in a pattern regardless of the number of rows and/or columns involved. A single row may be referred to as either a "linear array" or a "strip lens".
If lens arrays are to be used for imaging purposes, it becomes necessary to isolate light channels between opposed lenses and thereby eliminate "crosstalk". This poses a serious problem in an integrally molded device.
The possibility of creating a strip lens by grinding and polishing individual glass or plastic rods has been recognized. The individual cylinders would then be arranged in a pattern and bonded in a fixed relation. However, the extreme problems of production and alignment have also been recognized.
Accordingly, a currently commercial imaging device relies on optical effects generated by an array of minute areas and/or rods, each having a defined gradient refractive index distribution. The array is produced by bundling a configuration of optical fibers wherein each fiber has a defined gradient index distribution imparted thereto as by ion exchange or material impregnation.